Device for putting under tension the tools of filing, sawing, and similar machines and machine tools



Aug. 6, 1929. THIEL- 1,723,389

DEVICE FOR PUTTING UNDER TENSION THE TOOLS OF FILING, I

SAWING, AND SIMILAR MACHINES AND MACHINE TOOLS Filed April 3 1929 m I v 9 J12 yen for all Patented Aug. 6, 1929.

UNITED STATES PATENT OFFICE.

HEINRICH THIE'L, OF RUHLA, GERMANY.

DEVICE FOR PUTTING UNDER TENSION THE TOOLS OF FILING, SAWING, AND SIMI- LAR MACHINES AND MACHINE TOOLS.

Application filed April 3, 1929, Serial No.

lVith machine tools. such as filing and sawing machines and thelilie, the tool generally attached to a bow or bow-l ke member and put Under tension therein by tightening a nut. This procedure is disadvzmtageous in that there no certainty as to when the proper degree ol tension has been attained so that it is no rare occurrence that the respective tool is damaged, especially torn.

Detrimental occurrences ol. this and similar kinds are completely obviated by the present invention, the clmracteristic 'leature oil? which is this that a. frictimi clutch is insorted into the tensioning device in such a. manner that the lIQllSlOlllIlg procedure can be continued only as long as the. clutch memlers remain coupled. with one another but are d sengaged instantly when the resistance has reached or exceeds a certain predeter mined maximum. In this moment the tensioning means proper goes out 0t action so that the tool is securely prevented from any damage.

The invention is illustrated diagrammatically and by way of example on the accompanying: drawing on which Figure 'l is a sideu'iew ot a. tonsioning device designed for use in connection with a sawinp machine, and Fig. 2 is partly (letthand part) a side- 'view oi, and partly (righthand part) an axial section l'lufoiurh the members shown in the letthand upper corner of Fig. l, l i e'. 2 being drawn to a greatly enlarged scale relatively to Fig. 1.

On the drawing (1 denotes a pillft-Olf the jlrame ot the machine, and, i) is the tool which is a saw-blade in this case. The blade clamped last in a bow composed of the members 1:, (I and o and is guidei'l vertically by said 'l'ran'le. The blade 7) is clamped fast at its lower end by any suitable means such as a clamp do; which is either firmly attached tolhe member (2 of the bow or adjustably attached thereto. The upper end of the blade is attached by any suitable means to an axially movable bolt y located in the member 0 of the bow.

The uppermost portion of the bolt 7 1S screiwthreaded and carries a nut i by which the bolt is moved axially when it is turned. At the lower end of the nut is a flange 7n,

352,227, and in Germany March 1, 1928.

the rim of which is directed upwardly so as to term circular groove, and in this groove is located. a ring in, the lower part of which is shaped in conformity with said groove, as distinctly shown in Fig. 2.

Also the upper portion of the nut '21 threaded, and on this thread is a smaller or outer nut 0 engaging a circular recess provided in the upper portion of the ring in, and in this recess is housed a helical spring: 11- bearingr at its upper end on an outer shoulder of the nut 0 and at its lower end .on an inner shoulder of the ring or, in consemicnce whereof the conical lower end o'l. this rim is pressed into the conical groove of the nut ()wing to the friction thus produced between the nut 2'. and the ring m the. nut is trained automatically b the ring when this latter is turned manual y, and when the ring is turned in counter-clockwise direction the blade is put under tension. This procedure can e continued until the resistance to further tensioning of the blade has become greater than the friction between the memhers l: and m. From this moment the nut 7': comes to a standstill and the further ten shining action ceases.

As the spring it bears against the nut 0 its pressure can be varied or adjusted by turning said nut in the one or the other direction. but the pressure with which the conical portion of the member on pressed into the groove of the member Z: can be varied also by exchanging the spring ufor a weaker or a stronger one.

I wish it to be understood that I do not limit myself to all details oil the constructional form shown merely by way of example in the drawing. For instance, instead of conical friction "tacos flat or cylindrical ones can be used, the means for guiding the how (0, (Z, or its equivalent may differ from that shown in the drawing, the tool may be, for instance, a file or the like.

I claim:

A device for preventing ovortensioning of a tool in a machine tool comprising a nut havin an externally threaded portion and a conical flange and an internally threaded portion adapted to cooperate with a tool securing belt of the machine tool; a ring;

provided around said nut adjacent the flange, having a shoulder and forming a spaced portion with the nut; an outer nut threaded on the screwthreaded portion of the first nut and having a. shoulder thereon; and a spring arranged between the shoulders in the spaced portion and adapted to force the ring on the flange for frictional contacttherewith whereby rotation of the ring will rotate the first nut through the frictional contact until the first nut offers more resistance than the frictional Contact.

In testimony whereof I afl ix my signature.

HEINRICH THEEL. 

